Array panel for a transflective liquid crystal display device

ABSTRACT

An array panel for a transflective liquid crystal display device includes a substrate; a thin film transistor on the substrate; a first passivation layer covering the thin film transistor and having a first transmissive hole and an inclined portion surrounding the first transmissive hole; a transparent electrode on the first passivation layer, the transparent electrode contacting the thin film transistor; and a reflector over the transparent electrode, the reflector completely covering the inclined portion and having a second transmissive hole corresponding to the first transmissive hole.

[0001] This application claims the benefit of Korean Patent ApplicationNo. 2001-39638, filed on Jul. 4, 2001 in Korea, which is herebyincorporated by reference for all purposes as if fully set forth herein.

BACKGROUND OF THE INVENTION

[0002] 1. Field of the Invention

[0003] The present invention relates to a liquid crystal display (LCD)device and more particularly, to an array panel for a transflectiveliquid crystal display device.

[0004] 2. Discussion of the Related Art

[0005] In general, the LCD device includes two substrates, which arespaced apart and facing each other, and a liquid crystal layerinterposed between the two substrates. Each of the substrates includesan electrode and the electrodes of each substrate are facing each other,also. Voltage is applied to each electrode and an electric field isinduced between the electrodes. An alignment of the liquid crystalmolecule is changed by the intensity of the electric field, and the LCDdevice displays a picture by transmissivity of the light varyingaccording to the arrangement of the liquid crystal molecules.

[0006] Because the liquid crystal display device is not luminescent, itneeds an additional light source in order to display images, and theliquid crystal display device is categorized into a transmissive typeand a reflective type depending on the kind of light source.

[0007] In the transmissive type, a back light behind a liquid crystalpanel is used as a light source. Light incident from the back lightpenetrates the liquid crystal panel, and the amount of the transmittedlight is controlled according to the alignment of the liquid crystalmolecules. Here, the substrates must be transparent and the electrode ofeach substrate must also be formed of transparent conductive material.As the transmissive liquid crystal display device uses the back light asa light source, it can display a bright image in dark surroundings. Bythe way, because an amount of the transmitted light is very small forthe light incident from the back light, the brightness of the back lightshould be increased in order to increase the brightness of the LCDdevice. Consequently, the transmissive liquid crystal display device hashigh power consumption due to the back light.

[0008] On the other hand, in the reflective type LCD device, sunlight orartificial light is used as a light source of the LCD device. The lightincident from the outside is reflected at a reflective plate of the LCDdevice according to the arrangement of the liquid crystal molecules.Since there is no back light, the reflective type LCD device has muchlower power consumption than the transmissive type LCD device. However,the reflective type LCD device cannot be used in dark places because itdepends on an external light source.

[0009] Therefore, a transflective LCD device, which can be used both ina transmissive mode and in a reflective mode, has been recentlyproposed. A conventional transflective LCD device will be describedhereinafter more in detail.

[0010]FIG. 1 is a cross-sectional view of a conventional transflectiveLCD device. In FIG. 1, the conventional transflective LCD device has alower substrate 10 and an upper substrate 30, and the substrates 10 and30 are spaced apart from and facing each other.

[0011] A pixel electrode 20 is formed on the inner surface of the lowersubstrate 10 and connected to the thin film transistor (not shown)formed on the inner surface of the lower substrate 10. The pixelelectrode 20 includes a transmissive electrode 21 and a reflectiveelectrode 22. The reflective electrode 22 has a hole in which thetransmissive electrode 21 is located. The transmissive electrode 21 isformed of a transparent conductive material such as indium-tin-oxide(ITO) or indium-zinc-oxide (IZO), which has high transmittance. Thereflective electrode 22 is formed of an opaque conductive material suchas aluminum (Al), which has high reflectance and low resistivity.

[0012] Next, a color filter 40, which corresponds to the pixel electrode20, is formed on the inner surface of the upper substrate 30 and acommon electrode 50 is formed on the color filter 40. The commonelectrode 50 is also made of the transparent conductive material.

[0013] A liquid crystal layer 60 is disposed between the lower and uppersubstrates 10 and 30, and molecules of the liquid crystal layer 60 arearranged horizontally with respect to the substrates 10 and 30.

[0014] On the outer surfaces of the substrates 10 and 30, a firstretardation film 71 and a second retardation film 72 are arranged,respectively. The first and second retardation films 71 and 72 changethe polarized state of light. In case of the first and secondretardation films 71 and 72 having a phase difference of λ/4 (λ=550 nm),an incident circular polarized light changes into linear polarizedlight, and an incident linear polarized light changes into circularpolarized light.

[0015] A first polarizer 81 and a second polarizer 82 are arranged onthe outer surface of the first and second retardation films 71 and 72.The second polarizer 82 is an analyzer, and the transmission axis of thesecond polarizer 82 has an angle of 90 degrees with the transmissionaxis of the first polarizer 81.

[0016] Next, a back light 90 is located under the outside of the firstpolarizer 81. The back light 90 is used as a light source of atranmissive mode of the transflective LCD device.

[0017] This transflective LCD device is a normally white mode and insuch case, white light is emitted when voltage is not applied. By theway, the transflective LCD device is planned on the basis of thereflective mode. Accordingly, transmittance of the transmissive modebecomes only 50% of the transmittance of the reflective mode when thevoltage is not applied, and thus gray light is emitted in thetransmissive mode.

[0018]FIG. 2 illustrates the transflective LCD device to solve the aboveproblem. In FIG. 2, the transflective LCD device is divided into atransmissive region “A” and a reflective region “B”.

[0019] The transflective LCD device has a lower substrate 110 and anupper substrate 160 facing apart from each other. A first passivationlayer 120 is formed on the inner surface of the lower substrate 110, andthe first passivation layer 120 has a first trasmissive hole 122 in thetransmissive region “A”. A transmissive electrode 130 of a transparentconductive material is formed on the first passivation layer 120. Next,a second passivation layer 140 is formed on the transmissive electrode130, and a reflective electrode 150 is formed on the second passivationlayer 140. The reflective electrode 150 has a second transmissive hole152 exposing the transmissive electrode 130 on the first transmissivehole 122. On the other hand, a thin film transistor (not shown) isformed on the inner surface of the lower substrate 110, and the thinfilm transistor is connected electrically to not only the transmissiveelectrode 130 but also the reflective electrode 150.

[0020] A color filter 161 is formed on the inner surface of the uppersubstrate 160 and a common electrode 162 is formed on the color filter161.

[0021] Next, retardation films 171 and 172 are arranged on the outersurface of the lower and upper substrates 110 and 160, respectively.Polarizers 181 and 182 are arranged on the outer surface of therespective retardation film 171 and 172. A back light 190 is locatedunder the lower polarizer 181.

[0022] A liquid crystal layer 200 is disposed between the reflectiveelectrode 150 and the common electrode 162. The liquid crystal moleculesof the liquid crystal layer 200 are arranged horizontally with respectto the substrates 110 and 160. The liquid crystal layer 200 has apositive permittivity anisotropy value, so the liquid crystal moleculesare arranged parallel to a direction of the electric field inducedbetween the reflective electrode 150 and the common electrode 162 whenvoltage is applied to the electrodes 130, 150 and 162.

[0023] A phase difference of the liquid crystal layer depends on therefractive index anisotropy value (An) and the thickness (d) of theliquid crystal layer. Therefore, the phase difference of the liquidcrystal layer can be controlled by changing the thickness of the liquidcrystal layer.

[0024] Accordingly, as shown in FIG. 2, the first passivation layer 120has a first transmissive hole 122 so that the brightness in thetransmissive mode and the reflective mode may be made uniform. At thistime, it is desirable that the liquid crystal layer 200 in thetransmissive region “A” has twice thickness of the liquid crystal layer200 in the reflective region “B”.

[0025] The polarized situations of the transflective LCD device of FIG.2 are illustrated in FIGS. 3A and 3B and in FIGS. 4A and 4B.

[0026]FIGS. 3A and 3B shows the polarized states before and afterapplying voltage in the reflective mode, respectively. Here, thepolarized situations are represented according to a progressingdirection of the light. Meanwhile, y-axis is a direction parallel to thesubstrates 110 and 160 of FIG. 2 and z-axis is a direction perpendicularto the substrates 110 and 160. And x-axis is defined in a directionperpendicular to both the y-axis and the z-axis. Therefore, thetransmission axis of the upper polarizer 182 has an angle of 135 degreesto the x-axis and the transmission axis of the lower polarizer 181 hasan angle of 45 degrees to the x-axis as watched from the bottom of theliquid crystal panel. In the meantime, the transmission axis of theupper polarizer 182 has an angle of 45 degrees to the x-axis as watchedfrom the top of the liquid crystal panel.

[0027] At this time, the liquid crystal layer 200 disposed in thereflective region “B” of FIG. 2 has a phase difference of λ/4 and isright-circulary polarized before applying voltage.

[0028] The optical axis of the lower retardation film 171 of FIG. 2 isparallel to the y-axis and the lower retardation film 171 isright-handed. Therefore, an incident light of 45 degrees isright-circularly polarized and an incident light to be right-circularlypolarized is linearly polarized at an angle of 135 degrees. An incidentlight of 135 degrees is left-circularly polarized and an incident lightto be left-circularly polarized is linearly polarized at an angle of 45degrees.

[0029] On the other hand, the optical axis of the upper retardation film172 of FIG. 2 is parallel to the x-axis and the upper retardation film172 is left-handed. And thus an incident light of 45 degrees to thex-axis is left-circularly polarized and an incident light to beleft-circularly polarized is linearly polarized at an angle of 135degrees. Next, an incident light of 135 degrees to the x-axis isright-circularly polarized and an incident light to be right-circularlypolarized is linearly polarized at an angle of 45 degrees.

[0030] In FIG. 3A, as voltage is not applied to the transflective LCDdevice, a light is linearly polarized an angle of 45 degrees to thex-axis through the upper polarizer 182 of FIG. 2, and the linearlypolarized light is left-circularly polarized through the upperretardation film 172. Next, the left-circularly polarized light goesthrough the liquid crystal layer 200 disposed in the reflective region“B” to be linearly polarized at an angle of 45 degrees from theleft-circularly polarization. This linearly polarized light is reflectedat the reflective electrode 150 of FIG. 2, and so the progressingdirection of the light changes. Accordingly, the reflective light has apolarizing angle of 135 degrees to the x-axis. Next, the linearlypolarized light at an angle of 135 degrees is left-circularly polarizedthrough the liquid crystal layer 200 disposed in the reflective region“B”. The left-circularly polarized light is linearly polarized at anangle of 135 degrees again through the upper retardation film 172. Asthe linearly polarized light has a polarizing direction to coincide withthe transmission axis of the upper polarizer 182, the linearly polarizedlight is all transmitted. Therefore, the displayed picture becomeswhite.

[0031] Next, in FIG. 3B, when voltage is applied to the transflectiveLCD device, a light is linearly polarized at an angle of 45 degrees tothe x-axis through the upper polarizer 182 of FIG. 2, and the linearlypolarized light is left-circularly polarized through the upperretardation film 172. The left-circularly polarized light goes throughthe liquid crystal layer 200 disposed in the reflective region “B”without change of the polarized state. Next, the left-circularlypolarized light is reflected at the reflective electrode 150 of FIG. 2,and so the left-circularly polarized light is right-circularlypolarized. The right-circularly polarized light does not change throughthe liquid crystal layer 200 disposed in the reflective region “B”.Next, the right-circularly polarized light is linearly polarized at anangle of 45 degrees through the upper retardation film 172, and thelinearly polarized light has a direction perpendicular to thetransmission axis of the upper polarizer 182. Accordingly, the linearlypolarized light is not transmitted, and thus the displayed picturebecomes black.

[0032]FIGS. 4A and 4B shows the polarized states before and afterapplying voltage in the transmissive mode, respectively. At this time,the liquid crystal layer 200 disposed in the transmissive region “A” ofFIG. 2 has a phase difference of λ/2 before applying voltage.

[0033] In FIG. 4A, as voltage is not applied to the transflective LCDdevice, light incident from the back light 190 to the lower polarizer181 of FIG. 2 is linearly polarized an angle of 45 degrees to the x-axisthrough the lower polarizer 181, and the linearly polarized light isright-circularly polarized through the lower retardation film 171. Next,the right-circularly polarized light goes through the transmissiveelectrode 130 and the right-circularly polarized light isleft-circularly polarized through the liquid crystal layer 200 disposedin the transmissive region “A”. The left-circularly polarized light islinearly polarized at an angle of 135 degrees through the upperretardation film 172. As the linearly polarized light has a polarizingdirection to coincide with the transmission axis of the upper polarizer182, the linearly polarized light is all transmitted. Therefore, thedisplayed picture becomes white.

[0034] On the other hand, in FIG. 4B, when voltage is applied to thetransflective LCD device, light from the back light 190 is linearlypolarized an angle of 45 degrees to the x-axis through the lowerpolarizer 181 of FIG. 2, and the linearly polarized light isright-circularly polarized through the lower retardation film 171. Theright-circularly polarized light goes through the transmissive electrodeand the liquid crystal layer 200 disposed in the transmissive region “A”without change of the polarized state. Next, the right-circularlypolarized light is linearly polarized at an angle of 45 degrees throughthe upper retardation film 172, and the linearly polarized light has adirection to be perpendicular to the transmission axis of the upperpolarizer 182. Accordingly, the linearly polarized light is nottransmitted, and thus the displayed picture becomes black.

[0035] As stated above, different thickness between the transmissiveregion and the reflective region makes the displayed picture uniform andsubstantially dark in the black mode. Therefore, the contrast ratio ofthe transflective LCD device is increased and the quality of pictureimproves.

[0036] By the way, in the case of forming the transmissive hole 122 ofFIG. 2, an inclined portion is formed between the transmissive region“A” and the reflective region “B”, and the thickness of the liquidcrystal layer 200 disposed in the inclined portion changes continuously.Accordingly, when the voltage is applied to the transflective LCDdevice, a fringe field is produced in the inclined portion and adistortion occurs. Also, the phase difference of the liquid crystallayer varies in the region, and thus light leakage occurs.

[0037] The structure of the array panel for the transflective LCD deviceto prevent the leakage light like this is suggested in the Japanesepublication No. 2000-275660. FIG. 5 is the representative drawing of2000-275660.

[0038] As shown in FIG. 5, a thin film transistor, which includes adouble-layered gate electrode 8 and 9, an active layer 11, ohmic contactlayers 12, a source electrode 14 and a drain electrode 15, is formed ona substrate 1. A transparent electrode 13, which connects to the thinfilm transistor, is formed on the substrate 1. An interlayer 3 of aphotosensitive resin is formed on the thin film transistor and thetransparent electrode 13. The interlayer 13 has a transmissive holeexposing a part of the transparent electrode 13 and inclined portion 17.The inclined portion 17 is a border area between a transmissive regionand a reflective region. A reflector 4 or 5 is formed on the interlayer3, and the reflector 4 or 5 covers a part of the inclined portion 17. Aconcave-convex section 18 is formed between the interlayer 3 and thereflector 4 or 5 in order to increase reflection. In the array panel of2000-275660, the effective area of the transmissive mode and thereflective mode has to be equal in order to get a stable picture. Here,the inclined portion 17 does not belong to the transmissive mode or thereflective mode. Therefore, the inclined portion is neither thetransmissive region nor the reflective region. If one end of thereflector 4 or 5 is located on the inclined portion 17, the effectivearea of the transmissive region and the reflective region is notinfluenced even though there are a bit errors.

[0039] However, as stated above, the leakage light occurs in theinclined area 17. If the reflector 4 or 5 is formed covering all theinclined portion 17 in order to prevent the light leakage, the reflector4 or 5 contacts the transparent electrode 13, and thus galvaniccorrosion happens between the transparent electrode 13 and the reflector4 or 5. Accordingly, the reflector 4 or 5 should not contact thetransparent electrode 13 and must cover only a part of the inclinedportion 17.

SUMMARY OF THE INVENTION

[0040] Accordingly, the present invention is directed to an array panelfor a transflective liquid crystal display device that substantiallyobviates one or more of problems due to limitations and disadvantages ofthe related art.

[0041] An advantage of the present invention is to provide an arraypanel for a transflective liquid crystal display device in which aleakage light does not happen and has an increased contrast ratio.

[0042] Another advantage of the present invention is to provide an arraypanel for a transflective liquid crystal display device which has noafterimage.

[0043] Additional features and advantages of the invention will be setforth in the description which follows, and in part will be apparentfrom the description, or may be learned by practice of the invention.These and other advantages of the invention will be realized andattained by the structure particularly pointed out in the writtendescription and claims hereof as well as the appended drawings.

[0044] To achieve these and other advantages and in accordance with thepurpose of the present invention, as embodied and broadly described, anarray panel for a transflective liquid crystal display device includes asubstrate; a thin film transistor on the substrate; a first passivationlayer covering the thin film transistor and having a first transmissivehole and an inclined portion surrounding the first transmissive hole; atransparent electrode on the first passivation layer, the transparentelectrode contacting the thin film transistor; and a reflector over thetransparent electrode, the reflector completely covering the inclinedportion and having a second transmissive hole corresponding to the firsttransmissive hole. Here, the inclined portion slopes with an angle withrespect to the substrate, and thereby light reflected at the reflectorcorresponding to the inclined portion substantially goes out of sight.The angle is within a range of about 20 to 110 degrees. And the angle iswithin a range of about 42 to 70 degrees, and thereby the light entirelygoes out of sight. The first passivation layer includes one of abenzocyclobutene (BCB) and a photosensitive acrylic resin. The arraypanel further includes a second passivation layer disposed between thetransparent electrode and the reflector, and the second passivationlayer includes silicon nitride. The reflector is connected to thetransparent electrode. The array panel further includes a gate line anda data line crossing each other and being electrically connected to thethin film transistor.

[0045] In another aspect, an array panel for a transflective liquidcrystal display device includes a substrate; a thin film transistor onthe substrate; a first passivation layer covering the thin filmtransistor, the first passivation layer having a first transmissive holeand an inclined portion surrounding the first transmissive hole; areflector on the first passivation layer, the reflector completelycovering the inclined portion and having a second transmissive holecorresponding to the first transmissive hole; and a transparentelectrode over the reflector, the transparent electrode contacting thethin film transistor. The inclined portion slopes with an angle withrespect to the substrate, and thereby a light reflected at the reflectorcorresponding to the inclined portion substantially going out of sight.The angle is within a range of about 20 to 110 degrees. And the angle iswithin a range of about 42 to 70 degrees, and thereby the light entirelygoing out of sight. The first passivation layer includes one of abenzocyclobutene (BCB) and a photosensitive acrylic resin. The arraypanel further includes a second passivation layer disposed between thetransparent electrode and the reflector, and the second passivationlayer includes silicon nitride. And the array panel further includes agate line and a data line crossing each other and being electricallyconnected to the thin film transistor.

[0046] It is to be understood that both the foregoing generaldescription and the following detailed description are exemplary andexplanatory and are intended to provide further explanation of theinvention as claimed.

BRIEF DESCRIPTION OF THE DRAWINGS

[0047] The accompanying drawings, which are included to provide afurther understanding of the invention and are incorporated in andconstitute a part of this specification, illustrate embodiments of theinvention and together with the description serve to explain theprinciples of the invention.

[0048] In the drawings:

[0049]FIG. 1 is a cross-sectional view of a conventional transflectiveliquid crystal display device;

[0050]FIG. 2 is a cross-sectional view of another transflective liquidcrystal display device;

[0051]FIGS. 3A and 3B are drawings showing polarized situations beforeand after applying voltage in the reflective mode of FIG. 2;

[0052]FIGS. 4A and 4B are drawings of showing polarized situationsbefore and after applying voltage in the transmissive mode of FIG. 2;

[0053]FIG. 5 is a drawing of a conventional transflective LCD accordingto Japanese published application no. 2000-275660;

[0054]FIG. 6 is a plan view of showing an array panel according to afirst embodiment of the present invention;

[0055]FIG. 7 is a cross-sectional view corresponding to the line VII-VIIof FIG. 6;

[0056]FIG. 8 is a drawing of calculating an inclined angle in the arraypanel of the present invention; and

[0057]FIG. 9 is a cross-sectional view of the array panel according to asecond embodiment of the present invention.

[0058]FIG. 10 is a cross-sectional view of the array panel according toa third embodiment of the present invention.

DETAILED DESCRIPTION OF THE ILLUSTRATED EMBODIMENTS

[0059] Reference will now be made in detail to the illustratedembodiment of the present invention, which is illustrated in theaccompanying drawings.

[0060]FIG. 6 is a plan view of an array panel for a transflective liquidcrystal display device according to a first embodiment of the presentinvention, and FIG. 7 is a cross-sectional view corresponding to theline VII-VII of FIG. 6.

[0061] In FIG. 6 and FIG. 7, a gate electrode 221 is formed on asubstrate 210, and the gate electrode 221 is connected to a gate line222 extending horizontally in the context of the figures. The substrate210 is made of an insulating material such as glass, and the gateelectrode 221 and the gate line 222 are formed of a conducting materialsuch as a metal. A gate insulator 230 covers the gate electrode 221 andthe gate line 222. The gate insulator 230 can be made of silicon nitrideor silicon oxide. Next, an active layer 240 is formed on the gateinsulator 230, and the active layer 240 is made of amorphous silicon. Asource electrode 251 and a drain electrode 252 are formed on the activelayer 240. The source electrode 251 is connected to a data line 253,which extends vertically in the context of the figure and crosses thegate line 222 to define a pixel region “P”. Though not shown in thefigures, ohmic contact layers are formed between the active layer 240and the source and drain electrodes 251 and 252 to lower contactresistance between the active layer 240 and the two electrodes 251 and252.

[0062] A first passivation layer 260 covers the source electrode 251,the drain electrode 252 and the data line 253. The first passivationlayer 260 has a first contact hole 261, a first transmissive hole 262and an inclined portion 263. The first contact hole 261 exposes a partof the drain electrode 252, and the first transmissive hole 262 exposesa part of the substrate 210 through the gate insulator 230. The firsttransmissive hole 262 can be formed in only the first passivation layer260. The first passivation layer 260 is made of a benzocyclobutene (BCB)or a photosensitive acrylic resin. Next, a transparent electrode 270 isformed on the first passivation layer 260. The transparent electrode 270is located in the pixel region “P” and is connected to the drainelectrode 252 through the first contact hole 261. The transparentelectrode 270 is made of a transparent conducting material such as anindium-tin-oxide (ITO).

[0063] A second passivation layer 280 is formed on the transparentelectrode 270. The second passivation layer 280 has a second contacthole 281, which exposes a part of the transparent electrode 270. Thesecond passivation layer 280 is made of a silicon nitride. A reflector290 is formed on the second passivation layer 280. The reflector 290 ismade of a metal, which reflects light well like aluminum (Al), and isconnected to the transparent electrode 270 through the second contacthole 281. Then the reflector 290 acts as a reflective electrode. Thereflector 290 has a second transmissive hole 291, which exposes thetransparent electrode 270 placed in the first transmissive hole 262. Atthis time, the reflector 290 entirely covers the inclined portion 263.

[0064] If the reflector 290 contacts the transparent electrode 270 ofITO and is patterned by a wet etching method, galvanic erosion can occurat the contact area of the reflector 290 and the transparent electrode270. Therefore, the second passivation layer 280 makes the contact areasmall, which prevents or limits the galvanic erosion. The secondpassivation layer 280 can be omitted if the reflector 290 is formed by adry etching method.

[0065] Like this, the reflector covers the inclined portion locatedbetween the transmissive region and the reflective region in order tointercept the leakage light. At this time, the inclined portion shouldhave a fixed angle.

[0066]FIG. 8 is a drawing of calculating an inclined angle of theinclined portion in the array panel of the present invention.

[0067] As illustrated in FIG. 8, x-axis is defined in a directionparallel to the substrate 210 of FIG. 7 and y-axis is defined in adirection perpendicular to the x-axis. And also x′-axis is defined in adirection parallel to the incline plane of the inclined portion andy′-axis is defined in a direction perpendicular to the x′-axis. Thex′-axis and the y′-axis have an angle of “θ” to the x-axis and they-axis, respectively.

[0068] After light in the air passes through the upper substrate of thetransflective LCD device, it is refracted at the liquid crystal layerand goes to the incline plane of the inclined portion. When the lightincident upon the incline plane has an angle of “α” with respect to they-axis, the incident light must be reflected toward the region betweenthe y′-axis and the x-axis for the reflected light to go out of sight.Thus, the leakage light can be blocked. At this time, the reflectedlight makes an angle of “2θ-α” with the y-axis, and the “2θ-α” should belarger than the “α”. Therefore, the “θ” is bigger than the “α”.

[0069] Light incident from the outside to the transflective LCD devicehas an incidence angle of 0 to 90 degrees with respect to thelongitudinal axis of the substrate. Here, the incident light having anincidence angle near 0 degree is emitted with an angle similar to theincidence angle. Accordingly, the incidence angle of the incident lightis considered within a range of about 20 to 90 degrees.

[0070] If the refractive index of the air is “n₁”, the averagerefractive index of the liquid crystal layer is “n₂” and the incidenceangle of the incident light is “θ₁”, the transmission angle “θ₂” of thetransmitted light is calculated with the Snell's law(n₁·sin(θ₁)=n₂·sin(θ₂)). Here, the transmission angle “θ₂” is the sameas the angle “α”. When the “n₁” is 1, the “n₂” is 1.5 and the incidenceangle “θ₁” is within a range of about 20 to 90 degrees, the transmissionangle “θ₂” becomes about 13 to 42 degrees. Therefore, the “α” is withina range of about 20 to 90 degrees.

[0071] When a 12.1 inch panel, which is widely used for a notebook PC,is looked at from 30 centimeters away, the picture of the panel is seenwithout lowering of the contrast ratio at the maximum 30 degrees withrespect to the longitudinal axis of the substrate. As the incidenceangle “θ₁” of the incident light is about 30 degrees, the transmissionangle “θ₂” of the transmitted light, i.e. the angle “α”, becomes about20 degrees. It is possible that the incline plane is formed by aninclination angle of about 110 degrees and the inclination angle “θ”should be bigger than the angle “α”, and thus the inclination angle “θ”of the incline plane may be about 20 to 110 degrees.

[0072] On the other hand, as stated above, the maximum value of the “α”is 42 degrees. Accordingly, if the angle “α” is bigger than 42 degrees,the reflected light to all the incident light is made to go out ofsight. Consequently, the inclination angle “θ” should desirably bewithin an angle of about 42 to 70 degrees.

[0073] The inclination angle “0” can be controlled according to theprocess condition of forming the first passivation layer 260 of FIG. 7.For example, in case of forming the first passivation layer of the BCB,which is patterned in a dry etching method using an etching gas, theinclination angle “θ” is controlled by changing the dry etchingcondition. Generally, the gas for etching the BCB includes sulfurhexafluoride (SF₆) or oxygen (O₂). At this time, if the composition rateof the O₂ in the etching gas is large, the etched BCB has a smallinclination angle, and if the composition rate of the O₂ in the etchinggas is small, the etched BCB has a large inclination angle. This is thereason a photoresist layer, which is used in etch of the BCB, is removedquickly in proportion to a quantity of O₂. Besides, the gradient of theetched BCB is gentle if the pressure of the etching gas is low, and thegradient of the etched BCB is steep if the pressure of the etching gasis high.

[0074] Meanwhile, if a photosensitive resin such as acrylic resin isused as the first passivation layer, the physical properties of thephotosensitive resin can be changed or the light intensity of exposingthe border region can be controlled to change the inclination angle.Here, quick change in the exposing light intensity results in a gentleincline plane, and slow change in the exposing light intensity resultsin a steep incline plane.

[0075] In the present invention, if the inclination angle of theinclined portion is over 20 degrees, and then the leakage light can beintercepted. Therefore, the contrast ratio of the transflective LCDdevice increases.

[0076] In the first embodiment of the present invention, the reflectoris formed over the transparent electrode, but the reflector can beformed under the transparent electrode. This second embodiment of thepresent invention is described in the following.

[0077]FIG. 9 is a cross-sectional view of the array panel according tothe second embodiment of the present invention. A plan view of thesecond embodiment is similar to FIG. 6.

[0078] In FIG. 9, a thin film transistor “T” is formed on a substrate310 and the thin film transistor “T” includes a gate electrode 321, asource electrode 351 and a drain electrode 352. The gate electrode 321is formed on the substrate 310 and a gate insulator 330 covers the gateelectrode 321. And an active layer 340 as a channel of the thin filmtransistor “T” is formed on the gate insulator 330. Next, the sourceelectrode 351 and the drain electrode 352 are formed on the active layer340. Though not shown in the figures, ohmic contact layers are formedbetween the active layer 340 and the source and drain electrodes 351 and352.

[0079] A first passivation layer 360 covers the source electrode 351 andthe drain electrode 352. The first passivation layer 360 has a firsttransmissive hole 362 and an inclined portion 363. The firsttransmissive hole 362 exposes a part of the substrate 310 through thegate insulator 330. The first passivation layer 360 is made of abenzocyclobutene (BCB) or a photosensitive acrylic resin. Here, aninclination angle of the inclined portion 363 is over 20 degrees, and itis desirable that the inclination angle of the inclined portion 363 iswithin a range of about 42 to 70 degrees.

[0080] Next, a reflector 370 is formed on the first passivation layer360. The reflector 370 has an open portion 371 over the drain electrode352 and a second transmissive hole 372 corresponding to the firsttransmissive hole 362. The reflector 370 is made of a metal, whichreflects light well like aluminum (Al). At this time, the reflector 370entirely covers the inclined portion 363.

[0081] A second passivation layer 380 is formed on the reflector 370 andcovers the reflector 370. The second passivation layer 380 has a contacthole 381, which exposes a part of the drain electrode 352, through thefirst passivation layer 360 through the open portion 371. The secondpassivation layer 380 is made of a silicon nitride. The secondpassivation layer 380 over the transmissive holes 362 and 372 can beetched.

[0082] Next, a transparent electrode 390 is formed on the secondpassivation layer 380 and the transparent electrode 390 is connected tothe drain electrode 352 through the contact hole 361. The transparentelectrode 370 is made of a transparent conducting material such as anindium-tin-oxide (ITO).

[0083] In the second embodiment of the present invention, thetransparent electrode, which is made of the same material as a commonelectrode of the upper substrate, is formed on the top of the lowersubstrate, and then an afterimage can be cut off.

[0084]FIG. 10 is a cross-sectional view of the array panel according toa third embodiment of the present invention. A plan view of the thirdembodiment is similar to FIG. 6. The third embodiment is similar to thesecond embodiment, except that the first transmissive hole 362 and thesecond transmissive hole 372 corresponding to the first transmissivehole 362 do not extend through the gate insulation layer 330.

[0085] In FIG. 10, a thin film transistor “T” is formed on a substrate310 and the thin film transistor “T” includes a gate electrode 321, asource electrode 351 and a drain electrode 352. The gate electrode 321is formed on the substrate 310 and a gate insulator 330 covers the gateelectrode 321. And an active layer 340 as a channel of the thin filmtransistor “T” is formed on the gate insulator 330. Next, the sourceelectrode 351 and the drain electrode 352 are formed on the active layer340. Though not shown in the figures, ohmic contact layers are formedbetween the active layer 340 and the source and drain electrodes 351 and352.

[0086] A first passivation layer 360 covers the source electrode 351 andthe drain electrode 352. The first passivation layer 360 has a firsttransmissive hole 362 and an inclined portion 363. The firsttransmissive hole 362 exposes a part of the gate insulator 330. Thefirst passivation layer 360 is made of a benzocyclobutene (BCB) or aphotosensitive acrylic resin. Here, an inclination angle of the inclinedportion 363 is over 20 degrees, and it is desirable that the inclinationangle of the inclined portion 363 is within a range of about 42 to 70degrees.

[0087] Next, a reflector 370 is formed on the first passivation layer360. The reflector 370 has an open portion 371 over the drain electrode352 and a second transmissive hole 372 corresponding to the firsttransmissive hole 362. Like the first transmissive hole 362, the secondtransmissive hole 372 does not extend through the gate insulator 330.The reflector 370 is made of a metal, which reflects light well likealuminum (Al). At this time, the reflector 370 entirely covers theinclined portion 363.

[0088] A second passivation layer 380 is formed on the reflector 370 andcovers the reflector 370. The second passivation layer 380 has a contacthole 381, which exposes a part of the drain electrode 352, with thefirst passivation layer 360 through the open portion 371. The secondpassivation layer 380 is made of a silicon nitride. The secondpassivation layer 380 over the transmissive holes 362 and 372 can beetched.

[0089] Next, a transparent electrode 390 is formed on the secondpassivation layer 380 and the transparent electrode 390 is connected tothe drain electrode 352 through the contact hole 361. The transparentelectrode 370 is made of a transparent conducting material such as anindium-tin-oxide (ITO) or Indium Zinc Oxide (IZO).

[0090] In the third embodiment of the present invention, the transparentelectrode, which is made of the same material as a common electrode ofthe upper substrate, is formed on the top of the lower substrate, andthen an afterimage can be cut off.

[0091] It will be apparent to those skilled in the art that variousmodifications and made in the fabrication and application of the presentinvention without the spirit or scope of the invention. Thus, it isintended that the present the modifications and variations of thisinvention provided they come within appended claims and theirequivalents.

What is claimed is:
 1. An array panel for a transflective liquid crystaldisplay device, comprising: a substrate; a thin film transistor on thesubstrate; a first passivation layer covering the thin film transistor,the first passivation layer having a first transmissive hole and aninclined portion surrounding the first transmissive hole; a transparentelectrode on the first passivation layer, the transparent electrodecontacting the thin film transistor; and a reflector over thetransparent electrode, the reflector completely covering the inclinedportion and having a second transmissive hole corresponding to the firsttransmissive hole.
 2. The array panel according to claim 1, wherein theinclined portion slopes with an incline angle with respect to thesubstrate, such that light reflected at the reflector corresponding tothe inclined portion is substantially reflected out of a viewing range.3. The array panel according to claim 2, wherein the incline angle iswithin a range of about 20 to 110 degrees.
 4. The array panel accordingto claim 3, wherein the incline angle is within a range of about 42 to70 degrees.
 5. The array panel according to claim 1, wherein the firstpassivation layer includes one of a benzocyclobutene (BCB) and aphotosensitive acrylic resin.
 6. The array panel according to claim 1,further comprising a second passivation layer disposed between thetransparent electrode and the reflector.
 7. The array panel according toclaim 6, wherein the second passivation layer is transparent.
 8. Thearray panel according to claim 6, wherein the second passivation layerincludes silicon nitride.
 9. The array panel according to claim 1,wherein the reflector is connected to the transparent electrode.
 10. Thearray panel according to claim 1, further comprising a gate line and adata line, the gate line and the data line crossing each other and beingelectrically connected to the thin film transistor.
 11. An array panelfor a transflective liquid crystal display device, comprising: asubstrate; a thin film transistor on the substrate; a first passivationlayer covering the thin film transistor, the first passivation layerhaving a first transmissive hole and an inclined portion surrounding thefirst transmissive hole; a reflector on the first passivation layer, thereflector completely covering the inclined portion and having a secondtransmissive hole corresponding to the first transmissive hole; and atransparent electrode over the reflector, the transparent electrodecontacting the thin film transistor.
 12. The array panel according toclaim 11, wherein the inclined portion slopes with an incline angle withrespect to the substrate, such that light reflected at the reflectorcorresponding to the inclined portion is substantially reflected out ofa viewing range.
 13. The array panel according to claim 12, wherein theincline angle is within a range of about 20 to 110 degrees.
 14. Thearray panel according to claim 13, wherein the incline angle is within arange of about 42 to 70 degrees.
 15. The array panel according to claim11, wherein the first passivation layer includes one of abenzocyclobutene (BCB) and a photosensitive acrylic resin.
 16. The arraypanel according to claim 11, further comprising a second passivationlayer disposed between the transparent electrode and the reflector. 17.The array panel according to claim 16, wherein the second passivationlayer is transparent.
 18. The array panel according to claim 16, whereinthe second passivation layer includes silicon nitride.
 19. The arraypanel according to claim 11, further comprising a gate line and a dataline, the gate line and the data line crossing each other and beingelectrically connected to the thin film transistor.
 20. The array panelaccording to claim 11, further comprising a gate insulator between thesubstrate and the first passivation layer.